In fields involving microelectronic devices, sensors, and optical elements, the development of devices that are small relative to the state of the art, controllable, and conveniently and relatively inexpensively reproduced with a relatively low failure rate is important.
A well-known method of production of such devices is photolithography. According to this technique, a negative or positive resist (photoresist) is coated onto the exposed surface of a material. The resist then is irradiated in a predetermined pattern, and irradiated (positive resist) or nonirradiated (negative resist) portions of the resist are washed from the surface to produce a predetermined pattern of resist on the surface. This is followed by one or more procedures. For example, the resist may serve as a mask in an etching process in which areas of the material not covered by resist are chemically removed, followed by removal of resist to expose a predetermined pattern of the conducting, insulating, or semiconducting material on the substrate. According to another example, the patterned surface is exposed to a plating medium or to metal deposition under vacuum, followed by removal of resist, resulting in a predetermined plated pattern on the surface of the material. In addition to photolithography, x-ray and electron-beam lithography have found analogous use.
While the above-described irradiative lithographic methods may be advantageous in many circumstances, all require relatively sophisticated and expensive apparatus to reproduce a particular pattern on a plurality of substrates, and are relatively time-consuming. Additionally, no method of patterning nonplanar surfaces is commonly available according to these methods. In the field of electronic circuitry, an attempt is often made to save space by stacking planar circuit boards or chips, the boards or chips interconnected with auxiliary contacts. Alternately, a board or chip may be bent or otherwise formed in a nonplanar manner so as to save space, auxiliary contacts connecting components on different sides of the bend. All too often these auxiliary contacts are the cause of circuitry failure, and the attempt to move from the two-dimensional domain to a three-dimensional domain fails. Irradiative lithography provides no remedy to this complication, nor does it provide a method of conveniently and inexpensively reproducing an existing microelectronic circuit pattern, or the surface morphological features of other objects of interest.
Additionally, the above-described irradiative techniques are generally not amenable to the patterning of biological species such as proteins, as they typically utilize resists and solvents that are toxic to many biological species.
A need exists in the art for a convenient, inexpensive, and reproducible method of plating or etching a surface according to a predetermined pattern. The method would ideally find use on planar or nonplanar surfaces, and would result in patterns having features in the micron and submicron domain. Additionally, the method would ideally provide for convenient reproduction of existing patterns. Additionally, a need exists for the fabrication of surfaces that can pattern portions amenable to attachment of biological species, such as antibodies, antigens, proteins, cells, etc., on the micrometer scale.
The study of self-assembled monolayers (SAMs) is an area of significant scientific research. Such monolayers are typically formed of molecules each having a functional group that selectively attaches to a particular surface, the remainder of each molecule interacting with neighboring molecules in the monolayer to form a relatively ordered array. Such SAMs have been formed on a variety of substrates including metals, silicon dioxide, gallium arsenide, and others. SAMs have been applied to surfaces in predetermined patterns in a variety of ways including simple flooding of a surface and more sophisticated methods such as irradiative patterning.
Accordingly, a general purpose of the present invention is to solve problems associated with expense, complicated apparatus, and other complications associated with patterning surfaces for electronic, chemical, biological, and optical devices. One object is to provide a method of conveniently and reproducibly producing a variety of SAM patterns on planar and nonplanar surfaces, the patterns having resolution in the submicron domain, and being amenable to plating, etc. Another purpose of the invention is to facilitate the attachment of biomolecules on the submicron scale without loss of biological function. Another purpose of the invention is to provide a method of forming a template from an existing pattern having micron or submicron-domain features, the template conveniently reproducing the preexisting pattern.
Another general purpose of the invention is to provide optical elements and devices that are conveniently and inexpensively manufactured, and that are adaptable to a variety of systems.